In an automatic inoculating device, each sample is taken from a sample tank by the automatic device using a stylus and is then distributed on the substrate surface using the same stylus.
The stylus must be moved from one area of sample collection in the corresponding tank to an inoculating area in which the sample must be distributed, generally in a spiral pattern. The spiral pattern enables to obtain a variable concentration of the sample along the pattern.
However, the reading and interpretation of the culture results are generally difficult. Moreover, differences in concentration between the most extreme areas are not always sufficient, in particular when the sample is highly concentrated.